Method of cleaning out slag or clinder pockets of open hearth heating furnaces



March 2l, 1939. Q CAVANAGH 2,151,264

METHOD OF CLEAING OUT SLAG OR CINDER POCKETS OF OPEN HEARTH HEATING FURNACES Filed Oct. 5, 1937 2 Sheets-Sheet 2 Wiliam 6.' (h1/magi MLEMW `Patented Mar. 21,193.9

UNirl-:n STATES.,

2.151,26; rmrnon or cLEANmG our SLAG on CINDER POCKETS HEATING FURNACES William Curran Cavansgh, W

F ,OPEN HEABTH ashington., Pa., as-

signor to Cardo! Corporation, a corporation of ois Application octoter s, 1931, serial No. 161,436 zi claim. (c1. zes-sz) combustion chamber of the melting hearth to preheat the air or air and gas, employed for supporting combustion in said chamber. 'I'he strucv tures and methods employed for effecting this`^ heat exchange naturally vary in different types and makes of furnac. However, itis customary in all such furnaces to pass the hot gases through one or more slag or cinder pockets between the l5 time they leave the combustion chamber and enter the heat exchange structure. While passing through the slag or cinder pockets, the hot gases are permittedto expand which causes molten material, such as slag and cinders, oxidized from the melting .material in the hearth to be precipitated into the pockets. Operation of the furnace may be continued until slag accumulates in the pockets to such a level that the pockets will no longer, perform their intended function.

The furnace then must be shut down to permit the pockets to be cleaned out.

To accomplish this cleaning out operation, it is necessary to remove a door or a portion of one of the brick walls of each pocket to gain'access to the slag precipitated therein. As the slag is. for themost part, a molten mass when the fui'-v nace is iirst shut down, water is sprayed into the pockets to lower the temperature as quickly as possible. As soon as the temperature will .per-

mit, workmenin insulated clothing enter the pockets and commence the dlilicult task of removing the slag.

The method now commonly employed to re- -move the slag, which has solidified by the time.

40 the temperature in the pockets is lowered to a point where workmen can enter the same, is to vemploy pneumatic picks, sledges, and the like, to break up the slag into chunks of a size which can4 be handled readily. With this method.' it requires from sixtyfto eighty hours to clean ou the slagor cinder pockets of a furnace.

It is the primary object of this invention'to .provide an improved method of cleaning out the deposits in slag or cinder pockets in open hearth furnaces more quickly and easily than with the method now commonlyemployed, therebyA ma.- terially increasing the total number of production hours and decreasing the labor cost for each furnace. Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings forming a part ,of this speciilcation, and in which like numerals are employed to designate like parts throughout 5 thesame,

Figure lis a vertical sectional view taken through the hearth, the slag or cinder pockets and the checker chamber of a conventional form of open hearth heating furnace, E@

YFigure 2v is a vertical sectional view taken on line 2-2 of Fig. 1,

Figure 3 `is a horizontal sectional view taken on line 3 3 of Fig. 1,

lFigure '4 is a fragmentary vertical sectional 15 view through a slag or cinder pocket with the deposited slag prepared for being broken up in accordance with the method embodying this invention, and

Figure 5 is a similar view to Fig. 4, but illus- 2o trates the slag after it has been broken Aup in readiness for easy and quick removal from the cinder pockets.

In the drawings, wherein for the -purpose of illustration are shown the steps of the method g5 embodying this invention, when the method accomplishes the removal of slag deposited in the cinder pockets of av conventional form of open hearth furnace of the producer gas type. This furnace structure is shown by way of illustration 30 only, and it is not intended to in any way limit the invention to this or any other type of furnace structure because of this selection. 'I'he furnace structure shown includes a melting hearth 6 conventionally positioned within th combus- 35 tion chamber 1. At each end of the hearth and combustion chamber, theregis located'a cinder pocket 8 of a construction peculiar to this type of furnace. This cinder pocket communicates through passageways 9 and I0 with an air check- 4o er chamber Il and a gas checker chamber l2, respectively. The cinder pocket 8 also communicates with the melting hearth 6 and combustion chamber 'l through the series of passages I3 suitably angularly arranged and connected in series 45 to form a suitable flow path. The several gures only illustrate the checker chambers and slag or cinder pockets located at one end of the furnace structure. It is to be yunderstood that the same arrangement and co bination of elements is 50 provided at the remaining end of the furnace structure. It is to be understood that the checker chambers I l and l2 are provided with the desired arrangement of brick work to permit each chamber to perform-its intended work in the convenu tional manner. In furnaces burning tar or oil,

the discharge opening of the ilow path formed by the passageways I3 so that the air discharged into the combustion chamber adjacent theburner will support combustion of the fuel fed through ythe burner.

Inthe producer gas type of heating furnace illustrated in the drawings, the hot products of combustion, or waste gases, leave the combustion chamber by flowing through the -passageways I3 from which they enter the slag or' cinder pocket 8 at one end 'of the furnace. From the cinder pocket, the hot products of combustion flow through the passages 9 and I0 into the air and gas checker chambers I I and I2, respectively. .From the chambers II and I2, the hot gases are discharged to a stack, not shown, in the conventional manner. While passing through the checker chambers, the hot gases thoroughly heat the brick work arranged therein. While the' hot products of combustion are passing through the slag or cinder pocket 8, these hot gases are permitted to expand with the result that the slag or cinder particles are permitted to precipitate from' the hot gases to be deposited in the pocket.

Concurrently at the remaining end of the furnace, air and gas are caused to flow through the checker chambers I I and I2, respectively, into the cinder pocket 8 and through the passageways I3 into the combustion chamber 1 where the combined air and gas is ignitedand burned to efect heating of the material in the hearth 6. I'he infcoming, air and gas, during their passage through the checker chambers Hand I2, respectively, are heated to a proper temperature by the heat retained in the brick work located in the tw chambers. The furnace is operated in this manner for a period o f approximately t'en to fifteen minutes when suitable control valves are operated to effect reversal of use ofthe chambers and pockets. at the oppositeendsof the furnace. By this method of operation, the brick work in the checker chambers at one' end of the furnace is being heated by the products of combustion coming from the hearth while the incoming air and by-product gas owing through the remaining checker chambers at the opposite 'end of' the furnace are being heated by the heatv retained in thegbrick work in these chambers fromthe preceding period of operation when these checker chambers VWere being heated by the discharging products of combustion.

After the precipitated slag or cinders accumlevel where the furnace must be shut down.

Prior to placing the furnace in operation, it is best to cover certain portions of certain of the'4 brick walls of the'pockets with a false wall or lining. -It is not absolutely necessary that the pockets be lined, nor is 'it necessary to cover all of the walls of the pockets. For example', it is entirely unnecessary to cover the walls provided with the openings 9 and I0 that lead to the checker-chambers and the walls through which entrance to the pockets is obtained, either bya means of doors or 'by tearing away portions of the pocket walls. Entrance is usually obtained A method, which will be described in detail at a" later point. The preferred construction for this false wall or lining isA a temporary brick wall built in spaced relation to the permanent walls of the furnace with sand deposited in the space between the false wallsandthe permanent walls.

This construction may be very quickly and easily removed after the furnace is shut down' and entrance is had to the pockets. Figs. 1, 2 and 3 illustrate the false wall Vor lining Il as covering -`the opposite 'sides and the bottom of a slag or cinder pocket 8. Fig. 4 illustrates the pocket 8 `after the false wall or lining Il has been removed from between the deposited slag or cinders I5 and the side walls of the pocket. As the lining beneath the deposited mass I5 is not accessible, it is not removed,`

When the furnace is ilrst shut down, the accumulated slag or cinders in the pockets 8 are in a more or less molten state. After an entrance is madel into-both of the pockets, water is sprayed thereinto for the purpose of quickly reducing the temperature in the pockets and solidifying the deposited slag or cinders. As soon as the temperature in the pockets is lowered sufficiently,

workmenin insulated clothing enter the pockets for the purpose of cleaning out the deposits.

It is, at best, 'a difiicult job to break up the solidified deposits and remove the same from the pockets. In practicing my method, I am able to very quickly reduce the solidified Vdeposits to chunks of proper size to permitthem to be quickly and easily removed from ythe pockets. AI effect this reduction of the solidified mass by forming therein one orfmore drill holes I1 which may extend at any desired angle from the top surface of the same.

Into` the drill hole or drill holes, indestructible cartridges I8 are'inserted. -The type of inde-v structible cartridge Imprefer to employ is completely illlustrated and described in Patent No.

1,941,196; issued to Frank H. Armstrong, on December 26, 1933. Reference may be made to' this issued patent for a complete understanding of this cartridge. Briey described, it consists of a chambered main body which is. provided at one end with a discharge cap having formed V therein a plurality of discharge ports. The remaining end of the chambered body is suitably closed by a charging cap. At the 'discharge end of the chambered body, a. mpturablewall is provided which' gives way or ruptures upon the de'- velopment of a predeterminedpressure within the chamber. The material breaking pressure is provided by chargingthe chamberofthemainbody with liquid carbon dioxide'at a pressure of approximately 1,000 pounds per square inch. To effect release of the material breaking medium from the cartridge at a predetermined work performing pressure, the liquid carbon dioxide is quicklygasied by means of a chemical heater' the discharge portsl into the veins, crevices or cracks of4 the slag or cinder deposit. Expansion of this carbon dioxide gas eilectively shatters or breaks up the deposit into chunks of a size which maybe handled readily for removal from the Dockets.

If the discharge ports are obliquely arranged, as is shown in Fig. 2 of Patent No. 2,083,976, issued toFrank H. Armstrong, on June 15, 1937, the cartridges Il need not be tamped .in the drill holes. Thesefobliquely arranged discharge ports 15 prevent building up of pressure between the lower end of thecartrldge and thevinner end of the 'drill hole, and result in holding the cartridge within the drill hole.

It has been determined that the best results are 20 obtained by drilling the holes to a depth at least equal to two-thirds of the depth of the slag or cinder deposit. Best results are obtained when the bottom end of each drill hole is located approximately one foot from the floor of the pocket.

Fig. 5 illustrates the appearance of the slag deposit after it is broken up by the charges from the cartridges I8. The cartridges, of course, are loose within the broken up material and may be recovered for future use as the slag-is removed.

30' from the pockets.

y It will be appreciated that when the solidified slag or cinder is broken up by the charges from the cartridges, the temperature of the deposit still is extremely high. For the purpose of eflectn i to be clearly illustrated.

The advantages to be derived from the use of Q5 my method may be set forth as follows:

(l) Speeding up the cycle of cleaning out the cinder or slag pockets which result in:

(a) A direct labor saving, reducing to ap,-

,l proximately twenty-four hours the work. which '50 heretofore has taken from sixty to eighty hours,

(b) A material monetary saving by reducing nthe non-productive cleaning out furnace.

(2) A safe method of dislodging the deposits 55 within the pockets which is suitable for use in plants located within city limits normally not allowing explosives to be employed.

(3) No fumes to delay clearing out of material after successive shots are fired.

(r4) The released, highly compressed carbon dioxide gas effects a slow heaving action which is not harmful to the permanent walls of the furnaces and results in no concussion which would damage said walls. 65 tsr'rhe addition of a cooling medium, suon as water, to the drill holes and in and around the cartridges, :tends to cool the mass ofuslag period of the or cinders and'produces minute cracks, due to 70 contractioneiects, to givethe shell an hydraulic action when the gaseous charge is released, and keeps the cartridge or shell at a reasonable temperature before rlng. 4

I (6) The cartridges may' be employed either 75 with or without the use of a cooling medium and with the drill holes arranged at any desired angle relative to the top of the mass.

I have described above the preferred steps, and certain modifications thereof, which may be employed -in carrying out this method of quickly and easily effecting removal of the slag and cinder deposits from pockets designed to receive l the same. It is to be understood, however. that I do not desire to be limited to the exact steps las they have been disclosed, for variations `and modiiloations of the same falling within the accompanying claims are contemplated. I further do not intend to limit the application of my invention to any particularl open hearth heating furnace structure because of my illustration of one accepted form of the same.

Having thus described my invention, I claim:

1. 'I'he method of cleaning out deposits in slag or cinder pockets of open hearth heating furnaces which comprises the steps of confining in a container a charge of highly compressed gas,v and suddenly liberating saidgas into a depression formed in the mass of solidified slag or cinders, whereby expansion of the gas will reduce the mass to chunks of a size which may be readily removed from the pockets.

2. The method of cleaning out deposits in `lslag or cinder pockets of open hearth heating furnaces which comprises the steps of corining in a container a charge of non-gaseous carbon dioxide, raising the temperature of the charge to and above the critical temperature oi' the Vsame to create within said container a charge of highly compressed carbon dioxide gas'at a predetermined pressure capable of breaking up the deposits, and releasing said gaseous charge into a depression formed in said deposit when said predetermined pressure has been reached.

3. The method of cleaning out deposits in slag or cinderl pockets of open hearth heating -furnaces which comprises the steps of forming inl said deposit a drill hole, depositing in said drill hole a cooling medium, inserting-in said drill hole in heat exchange relation to said cooling medium a container in which is conilned a charge of Vhighly compressed gas, and suddenly liberating said gas into said drill hole, whereby expansion ,of the gas will reduce the mass to chunks of a size which may be 'readily removed from the pockets. i

4. The method of cleaning out deposits in slag or cinder pockets of open hearth heating furnaces which comprises the steps of forming in said deposit a drill hole. depositing in said drill hole a cooling medium, inserting in said drill -hole in. heat exchange relation to said cooling medium a container in which is confined a charge of non-gaseous carbon dioxide, raising the temperature of the charge to and above the critical temperature of the same 'to create within said container a highly 'compressed carbon dioxide gas Aat a predetermined pressure capable of breaking up the deposit, and'releasing said highly co'mpressed gas into the drill hole-whereby expansion 'of the gas will reduce the mass to chunks of a size which may be readily removed from the pockets.

5. The method of cleaning out deposits in slag or cinder pockets of open hearth heating furneces which comprises the steps of confining in a container aucharge of highly compressed gas, forming in said" deposit a drill hole, placing in said drill hole a charge of water, inserting the container in the drill hole in heat exchange relation to said water, and suddenly liberating said gas into the drill hole, whereby expansion of the gas reduces the mass to chunks of a size which may be readily removed from the pockets.

6. 'I'he method of cleaning out deposits in slag or cinder pockets of open hearth heating furnaces which comprises Vthesteps of forming in said deposit a. drill hole, depositing in said drill hole a cooling medium inthe form of water, inserting in said drill hole in heat exchange relation to said water a container in which is confined a charge cinco-gaseous carbon dioxide, raising thetemperature of the charge to and above the critical temperature of the same to create within said container ay charge of highly compressed carbon dioxide gas at a predetermined pressure capable of breaking up the deposit, and releasing said gaseous charge into lthe drill hole when said predetermined pressure has been reached.

Y '1. The method of cleaning out deposits in slag or cinder pockets of open hearth heating furnaces which comprises the steps of forming expansion spaces between the deposit and certain of the permanent walls of the pocket, coniining in a container a charge of highly compressed gas, and suddenly liberating said gas into a depression formed in the m'ass of solidified slag or cinders,

whereby expansion of the gas will result in breaking up the mass and spreading the same horizontally to ill said expansion spaces.

' 8. 'Ihe method of cleaningout deposits in slag or cinder pockets of open hearth heating furnaces which comprises the steps of forming expansion spaces between the deposit andlcertain of the permanent walls of the pocket, confining in a container a charge of non-gaseous carbon dioxide,

raising the temperature of the charge to and above the critical temperature of the same to create within said container a charge of highly compressed carbon dioxide gas at a predetermined pressure capable of breaking up the deposit, and releasing said gaseous `charge into a temporary false walls associated with said per.

marient walls prior to permitting the deposit t0 accumulate in said pocket, coniining in a conl tainer a charge of highly compressed gas, and suddenly liberatingsaid gas-into a depression formed in the mass of solidied slagl or cinders,

' whereby expansion of the gas will reduce the mass to chunks of a size which may be readily removed from the pocket.

'10. The method. of cleaning out deposits in slag or cinder pockets of open hearth heating furnaces which co mprlses reducingv the deposit to chunks of a size which may be readily removed from the pocket .by the application of the forces of expanding highly compressed gas in the veins and crevices of the deposit. i

1l. 'I'he method of cleaning out deposits in slag or cinder pockets of open hearth -heating furnaces which? comprises the steps of coniining -in a container a charge of highly compressed gas, and suddenly liberating said gas in the veins and crevices of the mass of solidified slag or cinders at a depthin excess of one-half the depth of the deposit. whereby expansion of the gas will reduce the mass to chunks of a size which may be readily removed from the pocket; 4

l2. The vmethod lof cleaning out deposits in slag or cinder pockets of open hearth heating furnaces which comprises the steps of confining in a container a charge of lnon-gaseous carbon dioxide, raising the temperature of the chargeto and above the critical temperature of the same to create within said container a 'charge of highly y compressed carbon dioxide gas at a predetermined pressure capable of breaking up the deposits, and A suddenly releasingv said gas inthe veins and.

crevices of the mass of solidiiied slag or cinders at a point relative tothe depth of the mass which is in excess of one-half the depth of the deposit, whereby expansion of the gas will reduce the mass to chunks of a size which may be readily removed r from the pocket.

13. The method of cleaning out deposits in slag or cinder pockets of open hearth heating furnaces which comprises' the steps of forming in the mass of solidified sla'g or 'cinders one or more substantially perpendicularly arranged drill holes which terminate at a depth in excess of one-half the depth of th'e deposit, and suddenly liberating substantially at the inner terminal of said drill hole a charge of highly compressed gas whereby expansion of the gas will reduce the mass to chunks I forming in said deposit a drill hole, depositing in y said drill hole a cooling medium, inserting in said drill hole in heat .exchange relation to said cooling medium the container in which is conned the charge of highly compressed gas, and suddenly liberating said gas into said drill hole,

whereby expansion of the gas will release the mass to chunks of a size which may be readily removed from the pocket. Y

. 15. The method of cle vning out deposits in slag 'p y or cinder pockets of open hearth heating furnaces which, comprises the steps of forming expansion spaces between the deposit and certain of the Apermanent walls of the pocket, forming in saidA deposit a drill hole, depositing in said drill hole a cooling medium, inserting in said drill Ihole in heat exchange relation to said cooling medium.

a container in which is conned a charge of nongaseous carbon dioxide, raising the temperature of the charge vto and above the critical temperature of the same to create within said container a highly compressed carbon dioxide gas at a predetermined lpressure capable of breaking 'up the deposit, and releasing said highly Acompressed gas linto thedrill hole, whereby expansion ofthe gas -will reduce the mass to chunks of a size which may be readily removed from the pocket. e

16. The method of cleaning outv deposits in slag or cinder pockets of open hearth heating *furnaces lwhich comprises the steps of confining in av container acharge of highly compressed gas, forming in said deposit a drill hole, formingexpansion spaces between the deposit and certain of the permanent walls of the pocket, placing insaid drill hole a charge of water, and inserting the container in the drill hole in heat exchange relation to said water.' and suddenly liberating said gas into the drill hole, whereby expansionA of the gas reduces the mass to chunks of a size which 17." The method `of cleaning ont deposi in slag or cinder pockets of open hearth hea g furnaces which comprises the steps of fo may be readily removed from the pocket.

expansion spaces between the deposit and ce ain of the permanent walls of. the pocket, forming in vdrill hole when said predetermined pressure has been reached. l

18. The method of cleaning out deposits in slag or cinder pockets of open hearth heating furnaces which comprises the steps of forming expansion spaces between the deposit and certain or' the permanent wallsof the pocket by the removal of temporary false walls associated with permanent walls prior to permitting the deposit to accumulate in said pocket, forming in said deposit a drill hole, depositing in .said drill hole a cooling vjmedium, inserting in said drill hole in heat exchange relation to said cooling medium a container i which is confined a charge of highly compressed gas, and suddenly liberating said gas into said drill hole, whereby expansion ofthe gas will'reducethemasstochunks ofa size which may be readily removed from the pockets.

19. The method of cleaning out deposits in slag or cinder pockets of open hearth heating furnaces which'comprises reducing the deposit to chunks of a size which may be readily removed from the pocket by the applicationof the forces of highly compressed gas which is expanded in a manner to effect horizontal spreadingof the deposit in a plurality of directions.

20. The method of cleaning out deposits in slag or cinder pockets of open hearth heating furnaces which comprises the steps of forming one or more expansion spaces between the deposit and the' permanent walls Aof thepocket, forming one or more drill holes in the deposit, and applying fluid pressure to the walls of the drill hole or holes in the proper directions to cause the deposit to spread into said expansion spaces and thereby be broken into chunksof a size whichmay be readily removed from-the pockets.

21. The method of cleaning out deposits in slag or cinder pockets of-open hearth heating furnaces which comprises the steps of forming one or more expansion spaces between the deposit and the permanent w'alls of the pocket, forming one or more drill holes in the deposit, and applying the expanding forces of highly compressed gas to the walls of the drill hole or holes in the Vproper direction to cause the deposit to spread into said'expansion spaces and thereby be broken v into chunks of a size which may be readily removed from the pockets.

WILLIAM CURRAN CAVANAGH. 

